Gamma correction for adjustable light source

Abstract

The present invention provides a projection apparatus comprising: a light source, a light source control unit for controlling the output of the light source; at least one spatial light modulator for modulating the illumination light from the light source by multiple pixel elements; and an optical system for projecting, onto a screen, the illumination light deflected by the spatial light modulator, wherein: the light source control unit 1) modulates the output of the illumination light from the light source during a modulation period of the spatial light modulator, and 2) non-linearly controls the gray scale of an image projected onto the screen.

Description

[0001]This application is a Non-provisional Application claiming a Priority date of Sep. 6, 2007 based on a previously filed Provisional Application 60 / 967,953 and a Non-provisional patent application Ser. No. 11 / 121,543 filed on May 4, 2005 issued into U.S. Pat. No. 7,268,932 and another Non-provisional application Ser. No. 10 / 698,620 filed on Nov. 1, 2003. The application Ser. No. 11 / 121,543 is a Continuation In Part (CIP) Application of three previously filed Applications. These three Applications are Ser. No. 10 / 698,620 filed on Nov. 1, 2003 now abandoned, Ser. No. 10 / 699,140 filed on Nov. 1, 2003 now issued into U.S. Pat. No. 6,862,127, and Ser. No. 10 / 699,143 filed on Nov. 1, 2003 now issued into U.S. Pat. No. 6,903,860 by the Applicant of this Patent Applications. The disclosures made in these Patent Applications are hereby incorporated by reference in this Patent Application.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates general...

AI Technical Summary

Benefits of technology

"The present invention provides an improved image display apparatus with a new technology to achieve adjustable and high performance display images with higher resolution of gray scales. The new technology is not limited by the display gray scale performance of conventional spatial light modulators, making it possible to achieve gamma correction in a projection apparatus without making complicated modifications or increasing production costs. The invention includes a light source control unit that modulates the output of the illumination light from the light source during a modulation period of the spatial light modulator, non-linearly controlling the gray scale of the projected image. The invention also includes a spatial light modulator with a higher resolution of gray scales, allowing for a higher gamma correction in the projection apparatus. The invention can be applied to a projection apparatus with a light source control unit that modulates the output of the illumination light by making an emission interval cycle of pulse emission of the light source variable. The invention can also be applied to a projection apparatus with multiple light sources for each color of illumination light."

Problems solved by technology

Even though there have been significant advances in recent years in the technology of implementing Electromechanical micro-mirror devices as spatial light modulators, there are still limitations and difficulties when these are employed to display high quality images.

Specifically, when an image is digitally controlled, the image quality is adversely affected because the image is not displayed with a sufficient number of gray scales.

The on-and-off states of a micro-mirror control scheme, such as that implemented in the U.S. Pat. No. 5,214,420 and by most conventional display systems, limits image display quality.

Due to the ON-OFF states implemented in conventional systems, there is no way to provide a pulse width shorter than the LSB.

A limited gray scale leads to lower image quality.

However, these types of light sources perform poorly in high-speed switching that alternates between the ON and OFF states.

The light source that is continuously turned on generates a large amount of heat and wastes light and electricity.

However, the achievable improvement of the gray scale performance would be very limited if the improvements are to be achieved only through the control of the spatial light modulator limited.

However, the disclosures including those included in the Information Disclosure Statement (IDS) have not provided effective solution to resolve the above discussed difficulties and limitations.

However, this mathematical operation for the γ correction is complicated because its use of a logarithm function.

Also, a larger scale operation circuit is required, which to increases the production costs of projection apparatuses.

However, in order to attain an acceptable accuracy of operation (i.e., conversion accuracy), the gray scale accuracy of the input data has to be increased (in other words, the number of bits has to be increased) before conversion, which forces the lookup table or the like to occupy a greater volume of memory, which increases the production costs of projection apparatuses.

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